Using radio waves to peer back in time
Astronomers are planning huge radio arrays to investigate the birth of the first structures.
July 23, 2012
|One way astronomers map star-forming regions is by looking for a specific signature of neutral hydrogen; this tells scientists where these hydrogen clouds are. An electron can be in two energy states, and as it transitions from the higher-energy state to the lower-energy one, it emits radiation with a wavelength of 21 centimeters. Due to the universe’s expansion, light from distant objects has been stretched into lower-energy, and longer wavelength, radiation. This 21cm line thus has been redshifted into the radio regime.|
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